Core blowing machines



March 6, 1962 A. H. PETERSON CORE BLOWING MACHINES 2 Sheets-Sheet 1 Filed June 16, 1960 WBH JIWQ March 6, 1962 A. H. PETERSON 3,023,467

CORE BLOWING MACHINES Filed June 16, 1960 2 Sheets-Sheet 2 IN V EN TOR.

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4 anew nits tats 3,023,467 Patented Mar. 6, 1962 3,623,467 CGRE BLOWING MACHINES Axel H. Peterson, 4431 th Ave., Rock Island, Ill. Filed .lune 16, 1960, Ser. No. 36,635 9 Claims. (Cl. 221t)) This invention relates to machines for forming hollow objects and specifically to apparatus for molding hollow sand cores and more particularly to cores made of thermosetting resin binder and sand.

This invention provides a machine for blowing shell cores through the bottom of a heated core box. By blowing the sand and resin upwardly through the bottom of a core box the need for sand and resin flow control, which is required when the sand and resin supply is placed over the core box, is eliminated. This invention provides improved apparatus for allowing the unset portion of the thermosetting resin binder and sand to fall back into the supply magazine leaving a thin shell in the heated core box and thus making the upwardly blowing shell core machine a practical device.

A main object of this invention is to provide a sand valve that can be closed when sand and resin is being blown from a container or magazine upwardly into a cavity of a heated metal core box and opened after the thermosetting resin binder and sand has formed a wall against the heated surface of the core box cavity to allow the unset portion of the sand and binder to flow through the valve back into the container.

Another object is to provide means for operating the sand valve which is responsive to the air pressure that forces the sand and binder into the core box.

A still further object of the invention is to provide a simple means for screening the air during the exhaust cycle and cleaning the screen by passing the air through the exhaust screen during the blow cycle.

An advantage of this invention is the novel arrangement whereby the entire cycle from blow to blow is accomplished by the introduction and exhaustion of the compressed air through one opening into the bottom of the machine.

A mixture of therrnosetting resin binder and sand will hereinafter in the specification be called sand.

The simplicity of construction and other objects and advantages of this invention will be apparent from the description and drawings in which:

FIGURE 1 is a front elevational view of the core blowing machine with certain portions being broken away and in section along the line AA in FIGURE 2 to illustrate the details of the sand valve and valve operating mechanism;

FIGURE 2 is a fragmentary plan view with the core box, blow plate and core box clamping mechanism removed to show details of the sand valve structure;

FIGURE 3 is a side elevation with the upper portion broken away on the line B-B of FIGURE 2 to illustrate details of the sand valve structure.

Referring now to the drawings, the numeral 1 refers generally to a base having four legs and having a concave top surface contoured to clear the downwardmost deflection of diaphragm 2 and backing plate 3 with the heads of a plurality of cap screws 4' functioning as stops against the lowermost surface of the concave top. Protruding downwardly from the base 1 is a boss 5 having an air passage 6 leading from the lowermost surface of the concave top of the base to a pipe 7 threaded into the side of the boss. This pipe 7 provides a passage for air from the supply means through a three-way air control valve which permits air under a pressure of about 40 to 50 pounds per square inch to enter the space between the diaphragm 2 and the concave surface of the base during the blow phase and to exhaust into the atmosphere during the exhaust cycle. The means for supplying the air at the above pressures and the threeway valve are not shown in the drawings. The diaphragm 2, which may be made of a reinforced rubber, is sandwiched between the backing plate 3 and the pipe flange 8 and secured by the cap screws 4 threaded into the pipe flange and passing through the backing plate and the diaphragm. The relatively restricted hole 9 in backing plate 3 delays the flow of air into the tube 10 until the diaphragm is deflected into the position shown by the dashed lines in FIGURE 3.

The body 11 is a cylinder, flanged on each end. The lower end of the body is secured to the base 1 by the cap screws 12 with the outer annular portion of the diaphragm 2 sandwiched between the lower flanged end of the body 11 and the base 1 to form a container or magazine for the sand 13. The head plate generally designated 14 covers the upper end of the body and is secured by cap screws 15 which are screwed into the flange of the body with a gasket (not shown) between the plate and the flange to make an airtight seal. Threaded into the head plate 14 is a plug 16 which seals the opening through which a charge of sand is inserted into the container. A box, defining a blowhead or sand distribution chamber 17, is comprised of the four walls 18, 19, 20 and 21 extending upwardly from the head plate 14 and terminating in smooth coplanar ends surrounding a discharge opening, part of said plate forming the bottom of the box. A removable blow plate 22, of non-heat-conducting material, held by four set screws 23 which are adjustable in lugs 24, covers the discharge opening and is the top of the box. This blow plate has one or more openings 25 which are spaced to register with the mouth of one or more cavities 26 in the metal core box 27 to establish direct communication between the cavities and the chamber 17. The cavities in the core box are shaped to form the shell core desired. The core box may have as many cavities as the length of the chamber 17 permits with the apertures in the blow plate adapted to the mouths of the cavities in the core ebox in regard to size, shape and number.

I have chosen to show the vertically split core box 27 positioned by adjustable stops 28 and 29 and clamped by piston type, spring return, air cylinders 30 and 31 actuated by compressed air at line pressure of about pounds per square inch through the pipes 32, 33, and 34 with the pipe 34 connecting to a three-way air control valve which is not shown in the drawings. The three-way valve between the pipe 34 and the compressed air source valves the compressed air to energize the cylinders 30 and 31 during the blow cycle and to exhaust the air from the cylinders during the exhaust phase. Frame members 35, 36 and 37 support the air cylinders and stop 2? in their respective relationship to the core box 27. It is obvious that other clamping means can be used such as diaphragm type of air cylinders or even screw clamps could be used with hand wheels to actuate the screws. In FIGURE 1 the clamp jaws 38 and 39 are attached to their respective piston rods of the air cylinders. Cylinder 31 should be arranged to clamp the core box before cylinder 30 urges jaw 38 against the core box by constricting the air passage of pipe 33. A horizontally split core box could be used in which case the clamp jaw 39 would be removed and the cylinder 31 rendered inoperative. The stops 28 and 29 would serve to position the core box over the blow plate with the holes serving sand to the core box cavities in communicating relationship to the holes in the blow plate.

Secured to, and depending from, that portion of the that the lower ends of the conduits are clear of the pipe flange 8 at its extreme upward position as is shown by the dashed lines in FIGURE 3. Straddling the two sand conduits 4t and 41 is a frame generally designated 42 having laterally extending lugs 43 and 44, as shown in FIGURE 1, which are respectively coactive with pins 45 and 46 to guide the frame in its reciprocal vertical movement and which also serve as seats for the two compression springs 47 and 48 which urge the frame downwardly and hold it normally open. The upper ends of the pins 45, 46 are anchored in the head plate 14. The downward movement of the frame 42 is translated through tube 10 to the pipe flange 8 and diaphragm assemblage to urge this assemblage into the downwardly depressed position shown in FIGURE 1. The tube It) has its top end closed by being screwed into a blind hole tapped in the center of the frame 42 and its lower end screwed into the pipe flange 8 thus permitting air to pass from a valved source through pipe 7, passage 6, restricted hole 9, then through a hole in the center of diaphragm 2 up through the tube 10 and out through holes 49 into the closed sand container comprising base 1, body 11 and head 14. The holes 49, of which there may be several, are covered by a fine wire screen i wrapped around the tube and over the holes and secured in place as by soldering. This screen, not shown in FIGURE 3, prevents the loss of sand through the holes 49 and down through tube 10 on the exhaust cycle.

The frame 42 is provided with three platforms 51, 52 and 53 for the cone shaped rubber stoppers or poppet valves 54, 55, 56 respectively, with the center of the platforms drilled and tapped to receive the threaded end of the cone shaped head cap screws 57, 58 and 59 which secure the rubber cones to their respective platforms.

In that portion of the head plate 14 which comprises the bottom of the box forming chamber 17 there are three holes 60, 61 and 62 having their lower ends countersunk, as indicated by numeral 63, at approximately the same angle as that of their respective cone shaped rubber stoppers or poppet valves 54, S5 and 56 to provide seats for the cones and thus function as a sand valve retaining the sand in the chamber 17 when in the position depicted in FIGURE 3 and allowing the sand to fall down and out of the chamber when in the position shown in FIGURE 1. The sand is free flowing with an angle of repose of approximately 37 degrees and readily falls out of the chamber 17 when the cones are retracted downwardly. The sand 13, while not so shown in FIGURE 1 for purposes of clarity, actually surrounds the conduits 4t), 41 and the tube 10 and reaches the chamber 17 by the pressure of the air in the container as will be explained hereinafter.

I have illustrated a device with two siphon sand conduits 40, 41 and with three sand valves; 51, 52, 53 and their respectively associated parts; but, it is obvious that the machine would work as well with one conduit and one or two valves, two conduits and one valve or any number of conduits and valves that would fit operatively within the area of the bottom of the chamber 17.

In operating this apparatus a vented core box 27 is first treated to prevent sticking of the sand to the walls of the cavities 26 in a manner well known to those skilled in the art, then heated to about 500 degrees Fahrenheit by means not shown, and inserted between the clamp jaws 38 and 39 as shown in FIGURE 1. The three-way air valve controlling the clamp cylinders is actuated, rigidly securing the core box in operative relationship to the blow plate 22. The three-way valve controlling the flow of air through pipe 7 into the space between the diaphragm and the concave upper surface of base 1 is next opened and the pressure of the air in this space forces the diaphragm, and in turn the pipe flange 8 and tube 10, upwardly and since the tube is secured at its upper end to the frame 14 the frame, of course, is also moved upwardly guided by the pins 45 and 46 passing through their respective lugs 43, 44 and compressing springs 47, 48.

The upward movement of the frame is interrupted when the rubber stoppers S4, 55 and 56 seat into their respective countersunk holes 69, 61 and 62. With the seating of the rubber stoppers the sand container is sealed except through the conduits 40, 41 which are open to atmosphere through chamber 17, blow holes 25 and the vents in the core box cavities. The air under a pressure of about to pounds per square inch then passes through the hole 9, through tube 14 and out of holes 49 into the sand container forcing the sand upward through the conduits 49, 41 into chamber 17 from which the sand is distributed through the blow holes 25 into the cavities of the core box. After about 20 seconds the thermosetting resin binder has bound the sand grains that are in close proximity to the hot walls of the core box cavities into a shell taking the shape of the cavities. The sand within the walls of this shell is still flowable and when the threeway valve controlling the air in the sand container is opened the pressure drops in the space under the diaphragm, the springs 47, 48 urge the frame 42, carrying the rubber stoppers, downward thus opening the holes 66, 61 and 62 allowing the sand to fall out of the chamber 17 back into the sand container. The unset sand in the core box cavities falls into the chamber thence through the holes 60, 61 and 62 into the container. To complete the operation the three-way valve controlling the core box clamps is opened releasing the core box which is then removed from the machine and reheated if additional curing is required before removing the finished shell core.

It will be apparent that the sand conduits 4i) and 41 can be secured to the frame 42 and instead of being in threaded engagement with the plate 14 they can be removably seated in the plate by the conduit ends and their respective seats in the plate having complementary tapers thus when the frame moves downward a space is opened between the ends of the conduits and the plate 14 allowing the sand in the chamber 17 to fall through the space into the container as it does through the holes 60, 61 and 62 hereinbefore described. The holes 60, 61, 62 and their respective poppet valves 54, S5 and 56 could be eliminated by using the space between the plate and the conduits as the escape port for the residual sand in the chamber 17 if the conduits moved down with the frame 42. This would be an especially useful modification if the machine was built for a special core box and the length of the chamber was limited to the extent that only the conduits would fit into the allotted area of the bottom of the chamber.

It will also be apparent that the diaphragm serves to translate the force exerted by air under pressure into vertical movement of the tube 10 and in turn the frame 42 and that other means could be used to reciprocate the frame'42.

It will be recognized that there may be occasions when a hollow core is undesirable or, in fact, impossible to mold when the cavity in the core box is so small that all the resin and sand set into a solid mass leaving no unset sand mixture to flow down and out during the exhaust cycle. On such occasions this invention still has an inherent advantage in that the sand mixture in the chamber 17 is not at all times in contact with the blow plate, which may in time become hot, but only during the blow cycle.

While I have described my invention with some degree of particularity I do not wish to be limited to the details of construction shown or to the combination and arrangement of the parts except as set forth in the following claims.

What I claim is:

1. In shell molding or like apparatus including a mold having a cavity and a blow hole into which a thermosctting or like mixture is introduced and out of which unset mixture is dischargeable, the improvement comprising: a pressurizable and depressurizable container for such mixture and having mixture supply passage means and separate mixture return passage means, said container being arranged with both of said passage means in communication with the blow hole for eifecting supply of mixture to the blow hole via the supply passage means when the container is pressurized and for enabling direct return of unset mixture to the container via the return passage means when the container is depressurized; means for pressurizing and depressurizing the container and valve means cooperative with the return passage means for closing said return passage means when the container is pressurized and for opening said return passage means when the container is depressurized.

2. The invention defined in claim 1, in which: the blow hole is downwardly directed to enable gravitational discharge of unset mixture and the return passage means is arranged at a level below the blow hole and is down wardly directed to the container to provide for gravitational return of such unset mixture to the container.

3. The invention defined in claim 1, in which: the valve means is responsive to pressure changes in the container for automatically closing and opening the return passage means respectively in accordance with pressurizing and depressurizing of the container.

4. The invention defined in claim 1, in which: the container has wall means sealed against the mold about the blow hole and said wall means includes a supply opening and a return opening respectively providing the communications of the supply and return passage means with the blow hole; the valve means is located within the container and is movable between open and closed positions as respects said return opening; and pressure-receivable means is associated with the container, including a movable member projecting into the container and connected to the valve means, said pressure-receivable means being arranged to be pressurized and depressurized respectively according to pressurizing and depressurizing of the container.

5. The invention defined in claim 1, in which: the container has a peripheral wall, spaced first and second end wall means joined to said peripheral wall and a movable partition wall sealed to the peripheral wall and separating the container into a mixture magazine between the partition wall and first end wall means and a pressurereceivable chamber between the partition wall and secnd end wall means, said first end wall means being sealed against the mold about the blow hole and having a supply opening and a return opening respectively providing the communications of the supply and return passage means with the blow hole; said chamber having a pressure inlet for pressurizing the chamber to move said partition wall and said partition wall having an orifice therethrough enabling pressurizing of the magazine; said valve means being located within the magazine and being movable between open and closed positions as respects said return opening; and means connecting the partition wall to the valve means to cause movement of the valve means to its closed and open positions respectively according to pressurizing and depressurizing of said chamher.

6. The invention defined in claim 1, in which: the valve means is responsive to pressure changes in the container for automatically closing and opening the return passage means respectively prior to pressurizing and subsequent to depressurizing of the container.

7. In shell molding or like apparatus including a mold having a cavity and a lower horizontal wall provided with a vertical blow hole through which a thermosetting or like mixture is introduced under pressure, the improvement comprising: a container disposed below the mold and having an upper chamber and a lower magazine for containing mixture, said chamber having a horizontal top wall abutting the underside of said mold wall and a partition wall spaced below the top wall and partitioning the chamber from the magazine, said top wall having a discharge opening in vertical register with the blow hole and said partition wall having a supply aperture and a return aperture, both opening upwardly to the chamber and downwardly to the magazine; valve means within the magazine and movable upwardly to close and downwardly to open the return aperture; means for pressurizing the magazine to expel mixture through the supply aperture to the mold via the chamber, discharge opening and blow hole; and means operative on the valve means in response to pressurizing of the magazine for moving the valve means upwardly to close the return aperture, said valve means being movable downwardly in response to depressurizing of the magazine to enable gravitational return of excess material to the magazine from the mold via the blow hole, discharge opening and chamber.

8. In shell molding or like apparatus including a mold having a cavity and a lower horizontal wall provided with a vertical blow hole through which a thermosetting or like mixture is introduced under pressure, the improvement comprising: a container disposed below the mold and having an upper chamber and a lower magazine for containing mixture, said chamber having a horizontal top wall abutting the underside of said mold wall and a partition wall spaced below the top wall and partitioning the chamber from the magazine, said top wall having a discharge opening in vertical register with the blow hole and said partition Wall having a supply aperture and a return aperture, both opening upwardly to the chamber and downwardly to the magazine, said magazine having at its bottom means including a pressure-receivable chamber and a piston movable upwardly and downwardly thereon, said piston having an orifice therethrough and a tube rising therefrom in communication With said orifice and opening within the magazine; means for pressurizing the pressure-receivable chamber to move the piston and tube upwardly and to pressurize the magazine via said orifice and tube for expelling mixture through the supply aperture; and valve means connected to the tube and movable upwardly and downwardly thereby to respectively close and open the return aperture.

9. The invention defined in claim 8, in which: the magazine is in the form of a cylinder having an annular wall and a closed lower end and the piston is a flexible coaxial diaphragm above said lower end and circumferentially connected to the annular wall.

Polzguter et al. May 21, 1957 Harrison Ian. 28, 1958 

